• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.245-248
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• 2011

A multi pulse rocket motor(MPRM) has several advantages compared to the single one. The range and the terminal velocity of the guided missile can be remarkably increased by the application of the pulse separation device(PSD) to the solid rocket motor which resulted in appropriate thrust distribution. In this study, the full scale heavy type dual pulse rocket motor with the bulkhead type PSD was designed, manufactured, and fire-tested. The bursting time and pressure of PSD were analyzed by the pressure, thrust and vibration results of static fire tests. As a result, the design requirement was verified that bursting pressure is lower than 30% of 2nd pulse operating pressure.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.6
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• pp.552-559
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• 2005

This paper describes an experimental study on the inertance pulse tube refrigerator using a small compressor. The purpose of this experimental study is to identify the performance of the inertance pulse tube refrigerator for various operating conditions and to obtain the optimum configuration. The dead volume effect is verified by two experimental apparatuses with different dead volumes between the compressor and the aftercooler. The refrigerator of the smaller dead volume shows better performance. The influence of operating frequency and charging pressure on the performance of the refrigerator is experimentally investigated. Reducing the regenerator mesh size improves the performance of the refrigerator. Finally, the inertance pulse tube refrigerator has maximum cooling capacity at the specific combination of the pulse tube length and the inertance tube length. The loss analysis is used to analyze and predict the optimum condition of the pulse tube refrigerator.

• Nuclear Engineering and Technology
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• v.51 no.1
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• pp.263-268
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• 2019

The $^3He$ proportional chamber is widely used for neutron measurement owing to its high neutron detection efficiency and simplicity for gamma-ray rejection. In general, the neutron and gamma-ray signals obtained from the $^3He$ proportional chamber can be easily separated by the difference in the pulse heights. However, for a high gamma-ray field, the gamma-ray signal cannot be precisely eliminated by the pulse height due to gamma-ray pulse pileup which causes the pulse height of gamma-ray pulse to increase and making the pulses due to neutrons and gamma rays indistinguishable. In this study, an improved algorithm for $n/{\gamma}$ discrimination using a parameter, which is the ratio of the rise time to the pulse height, is proposed. The $n/{\gamma}$ discrimination performance of the algorithm is evaluated by applying it to $^{252}Cf$ neutron signal separation from various gamma-ray exposure rate levels ranging 0.1-5 R/h. The performance is compared to that of the conventional pulse-height analysis method in terms of the gamma elimination ratio. The suggested algorithm shows better performance than the conventional one by 1.7% (at 0.1 R/h) to 70% (at 5 R/h) for gamma elimination.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.5
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• pp.53-59
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• 1997

This study has been performed to inmvestigate MRR(metal removal rate), REW(relative electrode wear), surface roughness, heat transumutation layer and microhardness distribution in cross-section of the machined surface with various pulse-on duration and peak pulse current, using the copper and graphite electrode on the heat treated STD11 which is extensively used for metallic molding steel with the EDM. The results obtained are as follows; a) There exists critical pulse-on duration(If Ip equals 5A, .tau. on is 50 .mu. s) which shows the the maximum MRR in accordance with peak oulse current and the MRR decreases when the pulse-on duration exceeds the critical pulse-on during because of the abnormal electric discharge. b) Safe discharge is needed to make maximum of MRR and the metalic organization must be complicated for discharge induction. c) Graphite has much more benefits than copper electrode when rapid machining is done without electrode wear. d) The most external surface has the highest microhardness because of car- burizing from heat analysis of the dielectric fluid and the lower layar of the white covered layer has lower microhar dness than base matal because of softening.

• Korean Journal of Clinical Laboratory Science
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• v.47 no.1
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• pp.28-34
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• 2015

Pulse wave velocity (PWV) is used to non-invasively estimate the severity of arteriosclerosis by measuring arterial stiffness. Increased arterial stiffness measured by PWV stands for progressive arteriosclerosis and is caused by atherosclerotic risk factors. This study is focused on how brachial-ankle pulse wave velocity (baPWV) is related to the leading risk factors for arteriosclerosis or atherosclerosis. Subjects were 114, 69 males and 45 females who are in 60's and had baPWV test for acute stroke. The results are as follows: the group with increased arterial stiffness showed significant increase in HbA1c, total cholesterol, BSBP (brachial artery systolic blood pressure), BDBP (brachial artery diastolic blood pressure), CSBP (central artery systolic blood pressure), CDBP (central artery diastolic blood pressure), augmentation index (AIx) and diabetes mellitus. Correlation analysis between baPWV and atherosclerotic risk factor showed significant relationship in age, HbA1c, LDL cholesterol, BSBP, BDBP, CSBP, CDBP and augmentation index. baPWV was independently related to age and BSBP in multiple linear regression analysis. The group with increased arterial stiffness was independently related to BDBP in multiple logistic regression analysis. This study might be meaningful in evaluating the relationship between arterial stiffness and atherosclerotic risk factor in a new way, and be helped to make various studies for cardiovascular disease.

• Proceedings of the IEEK Conference
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• 2000.06b
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• pp.330-333
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• 2000

With the recent development of the ultrahigh-speed optical time division multiplexed system, high-repetition rate optical-pulse stream generation is necessary. This is different from conventional approaches, which use fiber or integrated waveguide delay line circuits. The high-repetition-rate optical-pulse multiplication phenomenon occurs when the optical pulse's spectral width is greater than the transfer bandwidth of the coupler used. From the analysis, the output repetition rate can be controlled by using fiber couplers with different equivalent transfer bandwidths. The pulse seperation spacing is controlled by number of cascaded coupler in optical loop mirror coupler scheme.

• Proceedings of the IEEK Conference
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• 2004.06a
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• pp.27-30
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• 2004

This paper has been designed the TDMG(Time Delay Multiple Gaussian) pulse generator for UWB systems and analyzed the characteristics of UWB impulse. Composite two equal Gaussian pulses in a difference time lag, and then investigated TDMG pulse and modeled mathematically. Designed the TDMG pulse generator by ADS(Advanced Design System) to embody by using actual element with such mathematical model. As well as, this paper finally proved an excellence of the TDMG pulse generator by performing analysis through simulation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.6
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• pp.529-534
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• 2002

Recently, As the higher frequency in clock of digital system being demanded and the density of circuits gets high for purpose of making light and minimizing system, the study for solution of digital signal distortion being interested. In this paper, the distortion of square pulse caused by dispersion as it propagates along a single microstrip line and crosstalk between lines on the Multi-Transmission Lines (MTL) is investigated. The dispersion and crosstalk of pulse signals is analyzed regarding to the structure of transmission line such as relative permittivity, substrate height, strip width of the microstrip line and pulse width of signal pulse.

• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.230-231
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• 2002

Recently, analysis of transient Raman backscattering in a plasma reported(2.3) that it is possible to reach 10$\^$17/ W/cm$^2$ for 1 micrometer wavelength laser pulse with a counter-propagating pump pulse. The basic mechanism is like this ： whorl the two counter-propagating waves in a plasma satisfy the condition of Raman backscattering, w$\_$0/ ： w$\_$1/ ＋ w$\_$p/, energy is transferred from the long pulse to the short pulse via three wave interaction(4). (omitted)

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.666-669
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• 2011

The rupture disc shapes of bulkhead type pulse separation device(PSD) are designed for new dual pulse rocket motor. Before final design PSD, that three different rupture disc are tested and confirmed the performance of the discs. Through analyzing the test results the PSD decides, two rupture disc shapes with flow holes of eight circles and eight trapezoids.